Liquid medicaments, such like insulin or heparin or other liquid medicaments such like vaccines that for instance require administering by way of injection, are typically provided and stored in vitreous cartridges, such like carpules, vials or ampoules. With regard to the type of medicament, the material of the cartridge or container has to be inert. Therefore, cartridges made of glass are nowadays typically used for storing and distributing such liquid medicaments.
Glass cartridges comprising a vitreous body of e.g. cylindrical geometry may become subject to fracture if not handled appropriately. In the event of undue care, glass cartridges may break. Even though in industrial filling and packaging processes, glass cartridges or vitreous bodies thereof are generally handled with due care, occasional breakage of particular cartridges may not be entirely prevented. In case a glass cartridge is damaged, glass splinters may distribute and the medicament contained in the cartridge may contaminate the environment, in particular neighbouring cartridges. In the event, a single glass cartridge is damaged in an industrial manufacturing line, it may become necessary that an entire charge of cartridges has to be visually inspected or discarded at high cost.
In addition, the quality of vitreous barrels or glass cartridges provided form a supplier may be subject to inevitable variations that arise from the glass production or manufacturing process of the respective cartridges.
Macroscopic glass breakage may occur due to a singular or due to repeated impact with a particular force or due to repeated and accumulated enlargement of macroscopic defects, the latter of which are not easily detectable. In typical production processes, a particular glass cartridge may be exposed to a series of low sized mechanical impacts. Any of these impacts alone does not yet lead to a macroscopic glass breakage. But accumulation of successive impact events may constantly lower the cartridge's integrity. This accumulation of mechanical microcracks or mechanical impact can be denoted as glass memory effect.
There exist various methods of testing or determining the glass integrity during or prior to a mass-production or filling process. Typically, the integrity of a vitreous body can be measured with a selection of tools by applying mechanical stress to the glass body from outside with a well-defined force until the glass body breaks or bursts. However, such burst experiments are difficult to control and may not provide sufficiently reproducible results that allow qualitative and quantitative comparison of different charges of cartridges.